which of the following are decomposition reactions?
a. CH^4 (g) + 20^2 (g) ->CO^2 (g) + 2H^2O (g)
b. CaCO^3 (s) -> CaO (s) + CO^2 (g)
c. N^2 (g) + 3H^2 (g) -> 2NH^3 (g)
d. 2H^2O (i) -> 2H^2 (g) + O^2 (g)

Check all that apply